We have devised procedures for the isolation, purification and eventual dissolution of the aerobic cell membrane from Rhodopseudomonas sphaeroides using chaotropic solutes. We than plan to characterize the protein components of this membrane species in order to determine if any of these protein species are found in the anaerobic cell membrane and in the chromatophore membrane system. At the present time we have been able to demonstrate using both protein chemistry and immunochemistry that better than 95% of the chromatophore membrane proteins are unique to the chromatophore. However, there is evidence to suggest that of the remaining 5%, there may prove to be identity between specific aerobic and anaerobic membrane proteins. Such a determination will then enable us to investigate precursor-product relationships under a variety of environmental conditions between all chromatophore proteins and their cellular components. In vivo density transfer experiments employing synchronized cell cultures reveal that protein components of the ICM are inserted at constant rates over the entire division cycle, whereas phospholipid is shown to accumulate in a temporal fashion. These studies coupled with the use of macromolecular mutants, in vivo kinetic experiments and in vivo density shift experiments should provide us with a sound experimental basis for understanding the development, synthesis and regulation of chromatophore specific organelles. BIBLIOGRAPHIC REFERENCES: Ding, V.H. and S. Kaplan. Separation and Purification of the Cell Membrane of R. sphaeroides. Preparative Biochemistry 6:61-79 (1976). Morgan, E. and S. Kaplan. The Expression of E. coli rDNA in Proteus mirabilis. J. Mol. and Gen. Genetics. 147:179-188 (1976).